Variable orifice meter

ABSTRACT

Variable orifice meter assembly for determining the total volume of gas flowing through the assembly by measuring only a portion thereof, comprising a positive displacement meter associated with a first stage input regulator and a second stage output regulator. The regulators are directly connected for gas flow therebetween and are also connected to the meter for gas flow from the input regulator through the meter to the output regulator. The output regulator is provided with a valve assembly comprising a secondary valve connected to a main valve, the main valve controlling the direct flow of gas from the input regulator to the output regulator and the secondary valve controlling the flow of gas through the meter. Both valves are mechanically activated for simultaneous unitary operation. The meter is activated by the portion of the total gas flowing therethrough but is calibrated so as to record the total flow of gas through the assembly.

United States Patent Hughes [541 VARIABLE ORIFICE METER [72] Inventor:George C. Hughes, Anderson, Ind.

[73] Assignee: Columbia'Gas System Service Corporation, Wilmington, Del.

[22] Filed: July 23, 1970 21 App1.No.: 57,457

[52] US. Cl. ..73/203, 137/601 [51] Int. Cl. ..G0lf 5/00, Fl7d H04 [58]Field of Search ..73/199, 201, 202, 203, 207, 73/208, 232-271; 137/110,599.1,115,

[56] References Cited UNITED STATES PATENTS 443,915 12/ 1 890 Goodwin etal. ..73/203 675,059 5/ 1901 Flint ..73/203 353,701 12/1886 Nash..73/203 353,702 12/1886 Nash ..73/203 353,700 12/1886 Nash ..73/203476,098 5/1892 Thomson ....73/203 1,247,330 11/1917 Roberts ..73/203[is] 3,691,831 [451 Sept. 19,1972

Primary Examiner-Richard C. Queisser Assistant Examiner-C. E. Snee, lllAttorney-Johnson & Kline [5 7] ABSTRACT Variable orifice meter assemblyfor determining the total volume of gas flowing through the assembly bymeasuring only a portion thereof, comprising a positive displacementmeter associated with a first stage input regulator and a second stageoutput regulator. The regulators are directly connected for gas flowtherebetween and are also connected to the meter for gas flow from theinput regulator through the meter to the output regulator. The outputregulator is provided with a valve assembly comprising a secondary valveconnected to a main valve, the main valve controlling the direct flow ofgas from the input regulator to the output regulator and the secondaryvalve controlling the flow of gas through the meter. Both valves aremechanically activated for simultaneous unitary operation. The meter isactivated by the portion of the total gas flowing therethrough but iscalibrated so as to record the total flow of gas through the assembly.

5 Claims, 6 Drawing Figures PAIENTEnsEP 19 m2 3.691. 831

sum 1 0F 3 INVENTOR.

Gay/1:76 C Huyfies VARIABLE ORIFICE METER It is known to use orificemeters to measure large flows of gas. The quantity of gas flowingthrough an orifice varies as the square root of the differentialpressure. Because of mechanical and installation limitations, theworking range of one orifice plate and one differential gauge is from amaximum capacity down to about one-fourth of maximum capacity. Themaximum and minimum capacity may be changed by changing the orifice sizebut this does not change the ratio therebetween as relates to workingcapacity.

It is also known to use rotary meters and turbine meters to measurelarge flows of gas but both of these types are limited in their abilityto measure low volumes of gas with accuracy.

The present invention is concerned with a mechanical variable orificemeter assembly adapted for the accurate measurement of the flow of bothlarge and small volumes of gas and having a working range of from zeroto maximum orifice capacity. The meter assembly of the present inventioncomprises a positive displacement meter, a first stage input regulatorof the pressure reducing type, a second stage output regulator of thepressure reducing type and a secondary valve connected to the main valveof the output regulator.

The input and output regulators, which may be of the type disclosed inmy US. Pat. No. 3,488,685, are connected to each other for the directflow of gas therebetween, controlled by the orifice of the main valve ofthe output regulator. Both regulators are also connected to the meterfor the flow of gas from the input regulator through the meter to theoutput regulator, controlled by the orifice of the secondary valve ofthe output regulator. The activation of the output regulator activatesthe interconnected valves to control the simultaneous flow of the totalgas volume in the form of two proportioned volumes. The larger volumebypasses the meter and flows directly through the main valve of theoutput regulator. The smaller volume passes through the meter, where itis measured, and through the secondary valve. Since the smaller volumerepresents a known proportion of the total volume, the meter can becalibrated to record the total volume of gas flowing through the system.

In the drawings:

FIG. 1 is a front view of a variable orifice meter assembly according tothe present invention;

FIG. 2 is an enlarged sectional view of a portion of the assembly ofFIG. 1;

FIG. 3 is a sectional front view of an output regulator of the presentmeter assembly, illustrating the valves in closed position;

FIG. 4 corresponds to FIG. 3 but illustrates the valves in openposition; and

FIGS. 5 and 6 are sectional front views of contoured valves suitable foruse in place of the secondary valve shown in FIGS. 2 to 4.

Referring to the drawings, FIG. 1 illustrates a variable orifice meterassembly comprising a first stage pressure reducing inlet regulator l ofthe constant pressure loaded type which delivers an accurate andconstant pressure to the main inlet 2 of second stage pressure reducingoutlet regulator 3 which delivers a constant outlet pressure regardlessof the travel of its main valve 4. The assembly also comprises a meter 5connected to outlet 6 of the first stage regulator 1 and connected tosecondary inlet 7 of the second stage regulator 3. The meter contains arecording index 8 calibrated to read out the total flow of gas throughthe assembly.

The first stage regulator I of FIG. I comprises a conventional diaphragmhousing 9 and conventional pilot regulator 10. Valve stem 11 isassociated with both the bell crank lever of the diaphragm (not shown)and the input regulator valve 12. When the pressure within the assemblyis lowered, through the use of gas, the diaphragm and bell crankleverare activated to raise the valve stem 11 and open valve 12permitting more gas to enter the assembly through first stage inlet 13.Incoming gas passes through valve 12 in open position and enters secondstage main inlet 2 and meter inlet 6. When in closed position, as shownin FIG. 2, valve 12 forms a gas-tight seal with the orifice bushing I4.

The second stage regulator of FIG. 2 also comprises a conventionaldiaphragm housing 15 containing a diaphragm associated with a bell cranklever (not shown) which in turn raises or lowers valve stem 16 and opensor closes connected main valve 4. A reduction in the gas pressure inoutlet 17 activates the diaphragm in regulator 3 causing valve stem 16to raise and open main valve 4 to permit more gas to flow through theassembly.

When in closed position, as shown in FIGS. 2 and 3, the seat of mainvalve 4 forms a gas-tight seal with the bushing 18 of orifice 19.

Valve 4 is connected to a secondary sliding valve 20 by means of a freepin 21 passing through an O-ring gland seal 22 and abutting valve 20.Pin 21 is held in positive contact with both the main valve 4 and thesecondary valve 20 by means of pressure from spring 23 against the baseof valve 20.

When in closed position, as shown in FIGS. 2 and 3, the resilient seat24 of sliding valve 20 forms a gas-tight seal with the orifice body 25in outlet swivel connection 26. An O-ring 27 provides a gas-tight sealbetween the orifice body 25 and swivel connection 26.

FIG. 4 shows the valves of the second stage output regulator in openposition for the flow of gas though the system. Activation of thediaphragm of output regulator 3 raises the valve stem 16 and opens mainvalve 4. Simultaneously the secondary valve20 is urged upward the samedistance as the main valve by means of spring 23 and pin 21 whichmaintains the valves equidistant at all times.

When the valves are in open position, gas is free to flow through theoutlet regulator directly from the inlet regulator 1, through main inlet2 and valve 4, and indirectly from the inlet regulator 1, through themeter 5 and secondary valve 20. As shown in FIG. 4, the secondarysliding valve 20 is provided with a slot constituting the orifice of thesecondary valve in open position. However other contoured valves 29 and30 provided with resilient seats 24, as illustrated by FIGS. 5 and 6,may be used in place of the valve 20 of FIGS. 2 to 4 to providedifferent linear flow rates.

The meter assembly of the present invention operates on the same orificeprinciple as known orifice meters in that the quantity of gas flowingthrough the meter varies as the square root of the differentialpressure. The generally accepted orifice formula is Q,, C 1/ h whereasin the modified formula ac-- cording to the present invention is 0,, CAI h P where:

Q, Quantity rate of gas flow at base conditions, cu.ft.lhr.

C Orifice flow constant per square inch of area.

hp Differential pressure in psi at 60 F.

P,= Outlet pressure, psi absolute.

' A A factor related to valve travel.

The valve of w/ h P, is constant as applied to this invention, as is C.The variable factor is A, which is directly proportional to valvetravel. Valve travel of the main valve 4 of regulator 3 causes a directand equal travel of secondary sliding valve 20. The two valves arepreferably designed so that the equal travel of the valves to openposition permits a much greater volume of gas to pass through valve 4than through valve 20. The relationship between the volumes of gaspassed by each valve can be determined and then the meter can becalibrated so as to extrapolate and'record the total gas flow throughtheassemblyby means of the measurement of that known portion of thetotal gas which passes through the meter.

valve 4 and a valve travel of from 0. to 0.l86 inch, a flow of 50cu.ft./hr. results at 0.001 ,inch travel and 5,000 cu.ft./hr. results at0.100 inch travel with a fixed 5 psi inlet pressure to the orifice and a7 inch W.C. outlet pressure. Valve travel of main valve 4 causes adirect and equal travel ofvalve but the size of the orifice 28 of valve20 is sufficiently smaller than that of the main valve that a valvetravel of 0.001 inch permits only one cu.ft./hr. of gas flow throughvalve 20 and a valve travel of 0.100 inch permits only 100 cu.ft./hr. ofgas flow through valve 20. Thus only one-fiftieth of the total gas flowpasses through the meter which can be calibrated to record a flow of .Xplus 50X for each X cu.ft./hr. of gas passing through the meter.

As will be clear to those skilled in the art in view of the presentdisclosure, the proportion of the total gas flow which passes throughthe meter may be varied by varying the size and design of the main valve4 and/or of the secondary-valve 20 whereby a greater or smallerproportion of the total gas flow bypasses the meter.

The unitary mechanical operation of the main and secondary valves of thepresent invention is highly advantageous for a number of reasons.Unconnected independent valves are subject to independent operationwhereby one valve might become defective and travel a greater or smallerdistance than the other. This destroys the original flow proportionrelationship calculated between the valves and leads to an inaccuratemeter reading. Also, if an electrical means is employed to activateeither or both of the valves, rather than the present mechanical means,this introduces a severe hazard in cases where the gas being measured isexplosive.

As will be clear to those skilled in the art, another pressure reducingregulator can be placed between the outlet of regulator l and the inletof meter 5 if the outlet pressure of regulator l is greater than theworking pressure of meter 5. Alternatively a combination regulator-metercan be used in such a situation in place of meter 5. Also the use of atemperature corrected meter can provide temperature correction tostandard conditions for the total gas flow.

Variations and modifications may be made within the scope of the claimsand portions of the improve- 20 For example, assuming a 56 inch orificel9 sealed by ments may be used without others.

lclaim; i 1. Variable orifice meter assembly for determining the totalvolume of gas flowing through the assembly by measuring only a portionthereof, which comprises a positive displacement meter, an inputregulator of the pressure reducing type which transmits the total volumeof the gas at a constant input pressure and which is connected to saidmeter, an output regulator of the pressure reducing type which transmitsthe total volume of gas at a constant outlet pressure, said outputregulator having a first connection to said input regulator and a secondconnection to said meter, and a mechanical valve assembly comprising amain valve and a secondary valve connected to'each other forsimultaneous unitary operation in opening and closing said connectionsto said output regulator, the orifices of said valves being in knowndirect proportion whereby the volume of gas which can flow through saidsecondary valve is in known direct proportion to the volume of gas whichcan flow through said main valve, said meter being adapted to measurethevolume of gas which flows through the meter whereby the total volume ofgas flowing through the assembly can be calculated.

2. Mechanical meter assembly according to claim 5 in which the metercomprisesa calibratedindex which calculates and records thetotal volumeof gas flowing through the assembly from that proportion of the totalvolume which passes through the meter.

3. Mechanical meter assembly according to claim 5 in which the orificeof the main valve is substantially larger than the orifice of thesecondary valve whereby only a minor proportion of the total gas volumemeasured by the assembly passes through the meter.

4. Mechanical meter assembly according to claim 5 in which the valveassembly comprises the main valve, the secondary valve, a free pinspacing the two valve and spring means adjacent the secondary valve foropening the secondary valve to correspond to the opening of the mainvalve. I

5. Variable orifice meter assembly for determining the total volume ofgas flowing through a main line by measuring only a portion thereofcomprising a positive displacement meter, a gas supply feeding gas undera constant pressure to a main line through said assembly, meter inletmeans associated with said main line for directing a portion of said gassupply from said main line through said meter, a regulator of thepressure reducing type connected to said main line including a mainvalve for controlling the flow of gas through said main line at aconstant pressure, a mechanical valve assembly activated by saidregulator and comprising said main valve and a secondary valve forcontrolling the flow of gas through said meter, said valves beingconnected to each other for simultaneous unitary operation in responseto the operation of said regulator, the orifices of said valves being inknown direct proportion whereby the volume of gas which can flow throughsaid secondary valve is in known direct proportion to the volume of gaswhich can flow through said main valve, said .meter being adapted tomeasure the volume of gas which flows through the meter whereby thetotal volume of gas flowing through the assembly can be calculated.

1. Variable Orifice meter assembly for determining the total volume ofgas flowing through the assembly by measuring only a portion thereof,which comprises a positive displacement meter, an input regulator of thepressure reducing type which transmits the total volume of the gas at aconstant input pressure and which is connected to said meter, an outputregulator of the pressure reducing type which transmits the total volumeof gas at a constant outlet pressure, said output regulator having afirst connection to said input regulator and a second connection to saidmeter, and a mechanical valve assembly comprising a main valve and asecondary valve connected to each other for simultaneous unitaryoperation in opening and closing said connections to said outputregulator, the orifices of said valves being in known direct proportionwhereby the volume of gas which can flow through said secondary valve isin known direct proportion to the volume of gas which can flow throughsaid main valve, said meter being adapted to measure the volume of gaswhich flows through the meter whereby the total volume of gas flowingthrough the assembly can be calculated.
 2. Mechanical meter assemblyaccording to claim 5 in which the meter comprises a calibrated indexwhich calculates and records the total volume of gas flowing through theassembly from that proportion of the total volume which passes throughthe meter.
 3. Mechanical meter assembly according to claim 5 in whichthe orifice of the main valve is substantially larger than the orificeof the secondary valve whereby only a minor proportion of the total gasvolume measured by the assembly passes through the meter.
 4. Mechanicalmeter assembly according to claim 5 in which the valve assemblycomprises the main valve, the secondary valve, a free pin spacing thetwo valve and spring means adjacent the secondary valve for opening thesecondary valve to correspond to the opening of the main valve. 5.Variable orifice meter assembly for determining the total volume of gasflowing through a main line by measuring only a portion thereofcomprising a positive displacement meter, a gas supply feeding gas undera constant pressure to a main line through said assembly, meter inletmeans associated with said main line for directing a portion of said gassupply from said main line through said meter, a regulator of thepressure reducing type connected to said main line including a mainvalve for controlling the flow of gas through said main line at aconstant pressure, a mechanical valve assembly activated by saidregulator and comprising said main valve and a secondary valve forcontrolling the flow of gas through said meter, said valves beingconnected to each other for simultaneous unitary operation in responseto the operation of said regulator, the orifices of said valves being inknown direct proportion whereby the volume of gas which can flow throughsaid secondary valve is in known direct proportion to the volume of gaswhich can flow through said main valve, said meter being adapted tomeasure the volume of gas which flows through the meter whereby thetotal volume of gas flowing through the assembly can be calculated.